U.S. patent number 4,197,120 [Application Number 05/764,680] was granted by the patent office on 1980-04-08 for electrophoretic migration imaging process.
This patent grant is currently assigned to Eastman Kodak Company. Invention is credited to Joseph Y. Kaukeinen, Hal E. Wright.
United States Patent |
4,197,120 |
Wright , et al. |
April 8, 1980 |
**Please see images for:
( Certificate of Correction ) ** |
Electrophoretic migration imaging process
Abstract
An improved electrophoretic migration imaging process is
disclosed wherein the improvement comprises the use of electrically
photosensitive particles containing a colorant having an absorption
maximum greater than about 410 nm. and having the formula: ##STR1##
wherein n represents 0 or 1; m represents 1 or 2; Ar represents an
aromatic group; Z represents the nonmetallic atoms to complete an
aromatic group; and each of R.sup.1, R.sup.2, R.sup.3, R.sup.4 and
R.sup.5 represents hydrogen, nitro, cyano, halogen, or one of
various specified organo groups.
Inventors: |
Wright; Hal E. (Rochester,
NY), Kaukeinen; Joseph Y. (Rochester, NY) |
Assignee: |
Eastman Kodak Company
(Rochester, NY)
|
Family
ID: |
27094606 |
Appl.
No.: |
05/764,680 |
Filed: |
February 2, 1977 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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645005 |
Dec 29, 1975 |
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Current U.S.
Class: |
430/32; 430/37;
430/41 |
Current CPC
Class: |
C09B
23/0066 (20130101); C09B 23/0075 (20130101); G03G
17/04 (20130101) |
Current International
Class: |
C09B
23/00 (20060101); C09B 23/01 (20060101); G03G
17/00 (20060101); G03G 17/04 (20060101); G03G
013/01 (); G03G 017/04 () |
Field of
Search: |
;96/1PE,1.5,1.2
;260/24TC ;204/181RE |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Martin, Jr.; Roland E.
Assistant Examiner: Goodrow; John L.
Attorney, Agent or Firm: Everett; John R.
Parent Case Text
This application is a Continuation in Part of our U.S. Pat.
application No. 645,005 filed Dec. 29, 1975 in the name of
Kaukeinen and Wright now abandoned.
Claims
We claim:
1. In an electrophoretic migration imaging process which comprises
subjecting an electrically photosensitive colorant material
positioned between at least two electrodes to an applied electric
field and exposing said material to an image pattern of radiation
to which the material is photosensitive, thereby obtaining image
formation on at least one of said electrodes, the improvement which
comprises using as at least a portion of said material an
electrically photosensitive colorant having an absorption maximum
greater than 410 nm. and having the formula: ##STR54## wherein n
represents 0 or 1;
m represents 1 or 2;
Ar represents a substituted or unsubstituted, carbocyclic or
heterocyclic aromatic ring having 6 to 20 ring atoms in the
aromatic ring;
Z represents the nonmetallic atoms necessary to complete a
carbocyclic or heterocyclic aromatic ring having 5 to 14 ring atoms
in the aromatic ring;
each of R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5, which may
be the same or different, when taken alone, represent hydrogen,
nitro, cyano, halogen, an alkoxy having 1 to 8 carbon atoms, a
saturated heterocyclic amino having 5 to 8 ring atoms; a
dialkylamino, diarylamino, dialkarylamino, or diaralkylamino
wherein the alkyl group contained in such amino is a substituted or
unsubstituted alkyl having 1 to 8 carbon atoms in the alkyl; a
substituted or unsubstituted alkyl having 1 to 8 carbon atoms in
the alkyl; a substituted or unsubstituted, carbocyclic or
heterocyclic aromatic ring group having 5 to 14 carbon atoms in the
aromatic ring, a carboxy ester having 1 to 4 carbon atoms, or an
amide having the formula
wherein R.sup.6 represents hydrogen or a substituted or
unsubstituted aromatic group or a substituted or unsubstituted
alkyl as defined above;
each of R.sup.1, R.sup.2, and R.sup.3, when taken together,
represent together with Z, the atoms necessary to complete a fused,
poly-nuclear carbocyclic or heterocyclic aromatic ring having 10 to
14 carbon atoms;
said substituents for said substituted alkyl and aromatic ring
groups contain from 1 to about 8 carbon atoms and are selected from
the group consisting of alkoxy, aryloxy, amino, hydroxy, biphenyl,
alkylamino, arylamino, nitro, cyano, halogen, alkyl and an alkyl,
aryl or amino substituted acyl group;
with the proviso that when m represents 1 and n represents 0, Ar
represents phenylene, and more than one of R.sup.4, R.sup.5 and the
substituents on Ar represent either nitro or cyano, then at least
one of R.sup.1, R.sup.2 or R.sup.3 represents diarylamino or
dialkylarylamino.
2. In an electrophoretic migration imaging process which comprises
subjecting an electrically insulating carrier material positioned
between at least two electrodes to an applied electric field and
exposing said carrier material to an image pattern of radiation,
said carrier material containing electrically photosensitive
particles which comprise at least one colorant component
photosensitive to said radiation, thereby obtaining image formation
on at least one of said electrodes, the improvement which comprises
using in at least a portion of said particles an electrically
photosensitive colorant component having an absorption maximum
greater than about 410 nm, and having the following formula:
##STR55## wherein n represents 0 or 1;
m represents 1 or 2;
Ar represents a substituted or unsubstituted, carbocyclic or
heterocyclic aromatic ring having 6 to 20 ring atoms in the
aromatic ring;
Z represents the nonmetallic atoms necessary to complete a
carbocyclic or heterocyclic aromatic ring having 5 to 14 ring atoms
in the aromatic ring;
each of R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5, which may
be the same or different, when taken alone, represent hydrogen,
nitro, cyano, halogen, an alkoxy having 1 to 8 carbon atoms, a
saturated heterocyclic amino having 5 to 8 ring atoms; a
dialkylamino, diarylamino, dialkarylamino, or diaralkylamino
wherein the alkyl group contained in such amino is a substituted or
unsubstituted alkyl having 1 to 8 carbon atoms in the alkyl; a
substituted or unsubstituted alkyl having 1 to 8 carbon atoms in
the alkyl; a substituted or unsubstituted, carbocyclic or
heterocyclic aromatic ring group having 5 to 14 carbon atoms in the
aromatic ring, a carboxy ester having 1 to 4 carbon atoms, or an
amide having the formula
wherein R.sup.6 represents hydrogen or a substituted or
unsubstituted aromatic group or a substituted or unsubstituted
alkyl as defined above;
each of R.sup.1, R.sup.2, and R.sup.3, when taken together,
represent, together with Z, the atoms necessary to complete a
fused, polynuclear carbocyclic or heterocyclic aromatic ring having
10 to 14 carbon atoms;
said substituents for said substituted alkyl and aromatic ring
groups contain from 1 to about 8 carbon atoms and are selected from
the group consisting of alkoxy, aryloxy, amino, hydroxy, biphenyl,
alkylamino, arylamino, nitro, cyano, halogen, alkyl and an alkyl,
aryl or amino substituted acyl group;
with the proviso that when m represents 1 and n represents 0, Ar
represents phenylene, and more than one of R.sup.4, R.sup.5 and the
substituents on Ar represent either nitro or cyano, then at least
one of R.sup.1, R.sup.2 or R.sup.3 represents diarylamino or
dialkylarylamino.
3. In an electrophoretic migration imaging process which comprises
subjecting an electrically insulating carrier material positioned
between at least two electrodes to an applied electric field and
exposing said carrier material to an image pattern of radiation,
said carrier material containing electrically photosensitive
particles which comprise at least one colorant component
photosensitive to said radiation, thereby obtaining image formation
on at least one of said electrodes, the improvement which comprises
using in at least a portion of said particles an electrically
photosensitive colorant component having an absorption maximum
greater than about 410 nm and having the following formula:
##STR56## wherein Ar represents a substituted or unsubstituted,
carbocyclic or heterocyclic aromatic ring having 6 to 20 ring atoms
in the aromatic ring;
each of R.sup.4 and R.sup.5, which may be the same or different,
represents hydrogen or a cyano group; and
each of R.sup.7 and R.sup.8, which may be the same or different,
when taken alone, represents a substituted or unsubstituted,
acyclic lower alkyl having 1 to about 8 carbon atoms or a
substituted or unsubstituted, carbocyclic aromatic ring having 6 to
about 14 ring atoms in the aromatic ring and R.sup.7 and R.sup.8,
when taken together, represent a pyrrolidinyl or a piperidino group
and said substituents for said substituted acyclic lower alkyl and
aromatic ring groups contain from 1 to about 8 carbon atoms and are
selected from the group consisting of alkoxy, aryloxy, amino,
hydroxy, biphenyl, alkylamino, arylamino, nitro, cyano, halogen,
alkyl and an alkyl, aryl or amino substituted acyl group.
4. In an electrophoretic migration imaging process which comprises
subjecting an electrically insulating carrier material positioned
between at least two electrodes to an applied electric field and
exposing said carrier material to an image pattern of radiation,
said carrier material containing electrically photosensitive
particles which comprise at least one colorant component
photosensitive to said radiation, thereby obtaining image formation
on at least one of said electrodes, the improvement which comprises
using in at least a portion of said particles an electrically
photosensitive colorant composition having an absorption maximum
greater than about 410 nm. and having the following formula:
##STR57## wherein Ar represents a substituted or unsubstituted,
carbocyclic or heterocyclic aromatic ring having 6 to 20 ring atoms
in the aromatic ring;
each of R.sup.4 and R.sup.5, which may be the same or different,
represents hydrogen or a cyano group; and
R.sup.9 represents a substituted or unsubstituted, acyclic lower
alkyl having 2 to about 8 carbon atoms or a substituted or
unsubstituted, carbocyclic aromatic ring having 6 to about 14 ring
atoms in the aromatic ring and said substituents for said
substituted acyclic lower alkyl and aromatic ring contain from 1 to
about 8 carbon atoms and are selected from the group consisting of
alkoxy, aryloxy, amino, hydroxy, biphenyl, alkylamino, arylamino,
nitro, cyano, halide, alkyl and an alkyl, aryl or amino substituted
acyl group; ring group contain from 1 to about 8 carbon atoms and
are selected from the group consisting of alkoxy, aryloxy, amino,
hydroxy, biphenyl, alkylamino, arylamino, nitro, cyano, halogen,
alkyl and an alkyl, aryl or amino substituted acyl group;
5. In an electrophoretic migration imaging process which comprises
subjecting an electrically insulating carrier material positioned
between at least two electrodes to an applied electric field and
exposing said carrier material to an image pattern of radiation,
said carrier material containing electrically photosensitive
particles which comprise at least one colorant component
photosensitive to said radiation, thereby obtaining image formation
on at least one of said electrodes, the improvement which comprises
using in at least a portion of said particles an electrically
photosensitive colorant component having an absorption maximum
greater than about 410 nm. and having the following formula:
##STR58## wherein Ar represents a substituted or unsubstituted,
carbocyclic or heterocyclic aromatic ring having 6 to 20 ring atoms
in the aromatic ring;
each or R.sup.4 and R.sup.5, which may be the same or different,
represents hydrogen or a cyano group; and
each of R.sup.9, R.sup.10 and R.sup.11, which may be the same or
different, represents a substituted or unsubstituted, acyclic lower
alkyl having 2 to about 8 carbon atoms, or a substituted or
unsubstituted, carbocyclic aromatic ring having 6 to about 14 ring
atoms in the aromatic ring and said substituents for said
substituted acyclic lower alkyl and aromatic ring contain from 1 to
about 8 carbon atoms and are selected from the group consisting of
alkoxy, aryloxy, amino, hydroxy, biphenyl, alkylamino, arylamino,
nitro, cyano, halogen, alkyl and an alkyl, aryl or amino
substituted acyl group.
6. In an electrophoretic migration imaging process which comprises
subjecting an imaging suspension positioned between at least two
electrodes to an applied electric field and exposing said
suspension to an image pattern of radiation, said suspension
containing an electrically insulating carrier liquid and
finely-divided, electrically photosensitive particles which
comprise at least one colorant component photosensitive to said
radiation, thereby obtaining image formation on at least one of
said electrodes, the improvement which comprises using in at least
a portion of said particles an electrically photosensitive colorant
component having an absorption maximum greater than about 410 nm.
and having the following formula: ##STR59## wherein n represents 0
or 1;
m represents 1 or 2;
Ar represents a substituted or unsubstituted, carbocyclic or
heterocyclic aromatic ring having 6 to 20 ring atoms in the
aromatic ring;
Z represents the nonmetallic atoms necessary to complete a
carbocyclic or heterocyclic aromatic ring having 5 to 14 ring atoms
in the aromatic ring;
each of R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5, which may
be the same or different, when taken alone, represent hydrogen,
nitro, cyano, halogen, an alkoxy having 1 to 8 carbon atoms, a
saturated heterocyclic amino having 5 to 8 ring atoms; a
dialkylamino, diarylamino, dialkarylamino, or diaralkylamino
wherein the alkyl group contained in such amino is a substituted or
unsubstituted alkyl having 1 to 8 carbon atoms in the alkyl; a
substituted or unsubstituted alkyl having 1 to 8 carbon atoms in
the alkyl; a substituted or unsubstituted, carbocyclic or
heterocyclic aromatic ring group having 5 to 14 carbon atoms in the
aromatic ring, a carboxy ester having 1 to 4 carbon atoms, or an
amide having the formula
wherein R.sup.6 represents hydrogen or a substituted or
unsubstituted aromatic group or a substituted or unsubstituted
alkyl as defined above;
each of R.sup.1, R.sup.2, and R.sup.3, when taken together,
represent, together with Z, the atoms necessary to complete a
fused, polynuclear carbocyclic or heterocyclic aromatic ring having
10 to 14 carbon atoms;
said substituents for said substituted alkyl and aromatic ring
groups contain from 1 to about 8 carbon atoms and are selected from
the group consisting of alkoxy, aryloxy, amino, hydroxy, biphenyl,
alkylamino, arylamino, nitro, cyano, halogen, alkyl and an alkyl,
aryl or amino substituted acyl group;
with the proviso that when m represents 1 and n represents 0, Ar
represents phenylene, and more than one of R.sup.4, R.sup.5 and the
substituents on Ar represent either nitro or cyano, then at least
one of R.sup.1, R.sup.2 or R.sup.3 represents diarylamino or
dialkylarylamino.
7. In an electrophoretic migration imaging process as defined in
claim 6, the improvement which comprises using in at least a
portion of said particles an electrically photosensitive colorant
component having any one of the following formulas: ##STR60##
wherein Ar represents a substituted or unsubstituted, carbocyclic
or heterocyclic aromatic ring having 6 to 20 ring atoms in the
aromatic ring;
each of R.sup.4 and R.sup.5, which may be the same or different,
represents hydrogen or a cyano group; and
each of R.sup.7, R.sup.8, R.sup.9, R.sup.10 and R.sup.11, when
taken alone, represents a substituted or unsubstituted, acyclic
lower alkyl having 1 to about 8 carbon atoms or a substituted or
unsubstituted, carbocyclic aromatic ring having 6 to 14 ring atoms
in the aromatic ring group and, R.sup.7 and R.sup.8, when taken
together, represent a pyrrolidinyl or piperidino group and said
substituents for said substituted acyclic lower alkyl and aromatic
ring groups contain from 1 to about 8 carbon atoms and are selected
from the group consisting of alkoxy, aryloxy, amino, hydroxy,
biphenyl, alkylamino, arylamino, nitro, cyano, halogen, alkyl and
an alkyl, aryl or amino substituted acyl group.
8. In an electrophoretic migration imaging process as defined in
claim 6, the improvement which comprises using in at least a
portion of said particles an electrically photosensitive colorant
component having the formula: ##STR61## wherein Ar represents a
substituted or unsubstituted, carbocyclic or heterocyclic aromatic
ring having 6 to 20 ring atoms in the aromatic ring;
each of R.sup.4 and R.sup.5, which may be the same or different,
represents hydrogen or a cyano group; and
each of R.sup.7 and R.sup.8, when taken alone, represents a
substituted or unsubstituted, acyclic lower alkyl having 1 to about
8 carbon atoms or a substituted or unsubstituted, carbocyclic
aromatic ring having 6 to about 14 ring atoms in the aromatic ring
and R.sup.7 and R.sup.8, when taken together, represent a
pyrrolidinyl or a piperidino group and said substituents for said
substituted acyclic lower alkyl and aromatic ring groups contain
from 1 to about 8 carbon atoms and are selected from the group
consisting of alkoxy, aryloxy, amino, hydroxy, biphenyl,
alkylamino, arylamino nitro, cyano, halogen, alkyl and an alkyl,
aryl or amino substituted acyl group.
9. In a multicolor electrophoretic migration imaging process which
comprises subjecting an imaging suspension positioned between at
least two electrodes to an applied electric field and exposing said
suspension to an image pattern of activating radiation, said
suspension containing an electrically insulating carrier liquid and
a mixture of at least two differently colored, finely-divided,
electrically photosensitive particles, particles of one color being
photosensitive to a different spectral range of said radiation than
particles of a different color, at least some of said particles
comprising at least one colorant component photosensitive to some
portion of said radiation, thereby obtaining formation of a
multicolor image on at least one of said electrodes, the
improvement which comprises using in at least a portion of said
particles an electrically photosensitive colorant component having
an absorption maximum greater than about 410 nm. and having the
following formula: ##STR62## wherein n represents 0 or 1;
m represents 1 or 2;
Ar represents a substituted or unsubstituted, carbocyclic or
heterocyclic aromatic ring having 6 to 20 ring atoms in the
aromatic ring;
Z represents the nonmetallic atoms necessary to complete a
carbocyclic or heterocyclic aromatic ring having 5 to 14 ring atoms
in the aromatic ring;
each of R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5, which may
be the same or different, when taken alone, represent hydrogen,
nitro, cyano, halogen, an alkoxy having 1 to 8 carbon atoms, a
saturated heterocyclic amino having 5 to 8 ring atoms; a
dialkylamino, diarylamino, dialkarylamino, or diaralkylamino
wherein the alkyl group contained in such amino is a substituted or
unsubstituted alkyl having 1 to 8 carbon atoms in the alkyl; a
substituted or unsubstituted alkyl having 1 to 8 carbon atoms in
the alkyl; a substituted or unsubstituted, carbocyclic or
heterocyclic aromatic ring having 5 to 14 carbon atoms in the
aromatic ring, a carboxy ester having 1 to 4 carbon atoms, or an
amide having the formula
wherein R.sup.6 represents hydrogen or a substituted or
unsubstituted aromatic group or a substituted or unsubstituted
alkyl as defined above;
each of R.sup.1, R.sup.2, and R.sup.3, when taken together,
represent, together with Z, the atoms necessary to complete a
fused, polynuclear carbocyclic or heterocyclic aromatic ring having
10 to 14 carbon atoms;
said substituents for said substituted alkyl and aromatic ring
groups contain from 1 to about 8 carbon atoms and are selected from
the group consisting of alkoxy, aryloxy, amino, hydroxy, biphenyl,
alkylamino, arylamino, nitro, cyano, halogen, alkyl and an alkyl,
aryl or amino substituted acyl group;
with the proviso that when m represents 1 and n represents 0, Ar
represents phenylene, and more than one of R.sup.4, R.sup.5 and the
substituents on Ar represent either nitro or cyano, then at least
one of R.sup.1, R.sup.2 or R.sup.3 represents diarylamino or
dialkylarylamino.
10. An electrophoretic migration imaging dispersion comprising a
polymeric charge control agent, an electrically insulating carrier
material and an electrically photosensitive colorant material
characterized in that at least a portion of said
electrophotosensitive material comprises a colorant having an
absorption maximum greater than 410 nm. and the formula: ##STR63##
wherein n represents 0 or 1;
m represents 1 or 2;
Ar represents a substituted or unsubstituted, carbocyclic or
heterocyclic aromatic ring having 6 to 20 ring atoms in the
aromatic ring;
Z represents the nonmetallic atoms necessary to complete a
carbocyclic or heterocyclic aromatic ring having 5 to 14 ring atoms
in the aromatic ring;
each of R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5, which may
be the same or different, when taken alone, represent hydrogen,
nitro, cyano, halide, an alkoxy having 1 to 8 carbon atoms, a
saturated heterocyclic amino having 5 to 8 ring atoms; a
dialkylamino, diarylamino, dialkarylamino, or diaralkylamino
wherein the alkyl group contained in such amino is a substituted or
unsubstituted alkyl having 1 to 8 carbon atoms in the alkyl; a
substituted or unsubstituted alkyl having 1 to 8 carbon atoms in
the alkyl; a substituted or unsubstituted, carbocyclic or
heterocyclic aromatic ring group having 5 to 14 carbon atoms in the
aromatic ring, a carboxy ester having 1 to 4 carbon atoms, or an
amide having the formula
wherein R.sup.6 represents hydrogen or a substituted or
unsubstituted aromatic group or a substituted or unsubstituted
alkyl as defined above;
each of R.sup.1, R.sup.2, and R.sup.3, when taken together,
represent together with Z, the atoms necessary to complete a fused,
polynuclear carbocyclic or heterocyclic aromatic ring, having 10 to
14 carbon atoms;
said substituents for said substituted alkyl and aromatic ring
groups contain from 1 to about 8 carbon atoms and are selected from
the group consisting of alkoxy, aryloxy, amino, hydroxy, biphenyl,
alkylamino, arylamino, nitro, cyano, halide, alkyl and an alkyl,
aryl or amino-substituted acyl group;
with the proviso that when m represents 1 and n represents 0, Ar
represents phenylene, and more than one of R.sup.4, R.sup.5 and the
substituents on Ar represent either nitro or cyano then at least
one of R.sup.1, R.sup.2 or R.sup.3 represents diarylamino or
dialkylarylamino.
Description
FIELD OF THE INVENTION
This invention relates to electrophoretic migration imaging
processes and, in particular, to the use of certain photosensitive
pigment materials in such processes.
BACKGROUND OF THE INVENTION
In the past, there has been extensive description in the patent and
other technical literature of electrophoretic migration imaging
processes. For example, a description of such processes may be
found in U.S. Pat. Nos. 2,758,939 by Sugarman issued Aug. 14, 1956;
2,940,847, 3,100,426, 3,140,175 and 3,143,508, all by Kaprelian;
3,384,565, 3,384,488 and 3,615,558, all by Tulagin et al; 3,384,566
by Clark; and 3,383,993 by Yeh. In addition to the foregoing patent
literature directed to conventional photoelectrophoretic migration
imaging processes, another type of electrophoretic migration
imaging process which advantageously provides for image reversal is
described in Groner, U.S. Pat. No. 3,976,485 issued Aug. 24,
1976.
Certain important differences exist between the specific
electrophoretic migration imaging processes described, for example,
in the above-noted patents to Sugarman, Kaprelian, Tulagin et al,
Clark and Yeh, all of which deal with conventional electrophoretic
migration imaging processes, and the above-noted Groner U.S.
patent. The Groner application describes a novel method and
apparatus for obtaining image reversal as a consequence of the
electrical interaction between unexposed photosensitive particles
and a "dark charge exchange" electrode quite different from that
which occurs in conventional electrophoretic migration imaging
processes. However, there are certain general points of similarity
existing in each of the electrophoretic migration imaging processes
described in the foregoing patents.
In general, each of the foregoing electrophoretic migration imaging
processes typically employs a layer of electrostatic charge-bearing
photoconductive particles, i.e., electrically photosensitive
particles, positioned between two spaced electrodes, one of which
may be transparent. To achieve image formation in these processes,
the charge-bearing photosensitive particles positioned between the
two spaced electrodes, as described above, are subjected to the
influence of an electric field and exposed to activating radiation.
As a result, the charge-bearing electrically photosensitive
particles are caused to migrate electrophoretically to the surface
of one or the other of the spaced electrodes, and one obtains an
image pattern on the surface of these electrodes. Typically, a
negative image is formed on one electrode, and a positive image is
formed on the opposite electrode. Image discrimination occurs in
the various electrophoretic migration imaging processes as a result
of a net change in charge polarity of either the exposed
electrically photosensitive particles (in the case of conventional
electrophoretic migration imaging) or the unexposed electrically
photosensitive particles (in the case of the electrophoretic
migration imaging process described in the above-noted Groner
patent application) so that the image formed on one electrode
surface is composed ideally of electrically photosensitive
particles of one charge polarity, either negative or positive
polarity, and the image formed on the opposite polarity electrode
surface is composed ideally of electrically photosensitive
particles having the opposite charge polarity, either positive or
negative.
In any case, regardless of the particular electrophoretic migration
imaging process employed, it is apparent that an essential
component of any such process is the electrically photosensitive
particles. And, of course, to obtain an easy-to-read, visible image
it is important that these electrically photosensitive particles be
colored, as well as electrically photosensitive. Accordingly, as is
apparent from the technical literature regarding electrophoretic
migration imaging processes, work has been carried on in the past
and is continuing to find particles which possess both useful
levels of electrical photosensitivity and which exhibit good
colorant properties. Thus, for example, various types of
electrically photosensitive materials are disclosed for use in
electrophoretic migration imaging processes, for example, in U.S.
Pat. Nos. 2,758,939 by Sugarman, 2,940,847 by Kaprelian, and
3,384,488 and 3,615,558 by Tulagin et al, noted hereinabove.
In large part, the art, to date, has generally selected useful
electrically photosensitive or photoconductive pigment materials
for electrophoretic migration imaging from known classes of
photoconductive materials which may be employed in conventional
photoconductive element, e.g., photoconductive plates, drums, or
webs used in electrophotographic office-copier devices. For
example, both Sugarman and Kaprelian in the above-referenced
patents state that electrically photosensitive materials useful in
electrophoretic migration imaging processes may be selected from
known classes of photoconductive materials. And, the phthalocyanine
pigments described as a useful electrically photosensitive material
for electrophoretic imaging processes in U.S. Pat. No. 3,615,558 by
Tulagin et al have long been known to exhibit useful
photoconductive properties.
It is recognized, as set forth above, that many useful electrically
photosensitive materials which are employed in electrophoretic
migration imaging processes can be and have been selected from
known photoconductive materials. However, in accord with the
present invention it has unexpectedly been found after extensive
investigation of one particular class of known photoconductive
materials including, but not limited to, those materials described
in U.S. Pat. No. 3,246,983 issued Apr. 19, 1966, 3,567,450 issued
Mar. 2, 1971, 3,653,887 issued Apr. 4, 1972, and 3,873,312 issued
Mar. 25, 1975, that a particular subclass of these materials within
the larger class of organic photoconductive materials exemplified
by the above-noted patents are highly useful in electrophoretic
migration imaging processes as electrophotosensitive materials
and/or as chemical sensitizers for other electrophotosensitive
materials whereas many closely related materials within this same
class of known organic photoconductive materials show little or no
utility in electrophoretic migration imaging processes.
SUMMARY OF THE INVENTION
In accord with the present invention, it has been discovered that
electrostatic charge-bearing particles comprising an electrically
photosensitive colorant material having an absorption maximum to
visible light greater than about 410 nm. and having the following
formula are particularly suitable for use in electrophoretic
migration imaging processes: ##STR2## wherein: n represents 0 or
1;
m represents the integer 1 or 2;
Ar represents a substituted or unsubstituted, carbocyclic or
heterocyclic aromatic ring group, preferably having 6 to about 20
ring atoms in the aromatic ring, e.g., phenyl, naphthyl, anthryl,
etc.;
Z represents the nonmetallic atoms necessary to complete a
carbocyclic or heterocyclic aromatic ring group, preferably having
5 to about 14 ring atoms in the aromatic ring, e.g., phenyl,
anthryl, carbazole, pyrrole, etc.;
each of R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5, which may
be the same or different, when taken alone, represent hydrogen,
nitro, cyano, halogen, an alkoxy having 1 to 8 carbon atoms, a
saturated heterocyclic amino having 5 to 8 ring atoms; a
dialkylamino, diarylamino, dialkarylamino, or diaralkylamino
wherein the alkyl group contained in such amino is a substituted or
unsubstituted alkyl having 1 to 8 carbon atoms in the alkyl; a
substituted or unsubstituted alkyl having 1 to 8 carbon atoms in
the alkyl; a substituted or unsubstituted, carbocyclic or
heterocyclic aromatic ring group having 5 to 14 carbon atoms in the
aromatic ring, a carboxy ester having 1 to 4 carbon atoms, or an
amide having the formula
wherein R.sup.6 represents hydrogen or a substituted or
unsubstituted aromatic group or a substituted or unsubstituted
alkyl as defined above;
each of R.sup.1, R.sup.2 and R.sup.3, when taken together,
represent, together with Z, the atoms necessary to complete a
fused, polynuclear carbocyclic or heterocyclic aromatic ring group,
preferably an aromatic ring group having 10 to 14 carbon atoms, so
that each of R.sup.1, R.sup.2 and R.sup.3, when taken together, are
free from any saturated N-heterocyclic ring group fused to the
aromatic ring formed by Z;
with the proviso that (i) when m represents 1 and n represents 0,
Ar represents phenylene, and more than one of R.sup.4, R.sup.5, and
the substituents on Ar represent either nitro or cyano, then at
least one of R.sup.1, R.sup.2 or R.sup.3 represents diarylamino or
dialkarylamino.
A variety of different substituents may be present in the
above-defined formula in the case where Ar represents a substituted
aromatic group. In general, the substituents on Ar may be selected
from the same class of substituent groups defined above for
R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5.
When used in an electrophoretic migration imaging process, the
charge-bearing, electrically photosensitive particles of the
present invention are positioned between two spaced electrodes;
preferably these particles are contained in an electrically
insulating carrier such as an electrically insulating liquid or an
electrically insulating, liquefiable matrix material, e.g., a
thixotropic or a heat- and/or solvent-softenable material, which is
positioned between the spaced electrodes. While so positioned
between the spaced electrodes, the photosensitive particles used in
the invention are subjected to an electric field and exposed to a
pattern of activating radiation. As a consequence, the
charge-bearing, electrically photosensitive particles undergo a
radiation-induced variation in their charge polarity and migrate to
one or the other of the electrode surfaces to form on at least one
of these electrodes an image pattern representing a positive-sense
or negative-sense image of the original radiation exposure
pattern.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 represents diagrammatically a typical imaging apparatus for
carrying out the electrophoretic migration imaging process of the
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As noted hereinabove, many of the photosensitive materials which
have been found useful in the electrically photosensitive particles
used in the electrophoretic migration imaging processes of the
present invention have previously been found to possess useful
levels of photoconductivity. For example, U.S. Pat. Nos. 3,246,983,
3,567,450, 3,653,887 and 3,873,312 teach that certain of the
specific materials, which are described herein as useful in the
preparation of electrically photosensitive particles for
electrophoretic migration imaging processes, have previously been
identified as useful photoconductors. However, it has unexpectedly
been found that, while certain of the materials described as
photoconductors in U.S. Pat. Nos. 3,246,983, 3,567,450, 3,653,887
and 3,873,312 do provide useful electrically photosensitive
material for use in electrophoretic migration imaging processes,
many other quite similar photoconductive materials described in
these same patents have little or no utility in electrophoretic
migration imaging processes.
It is also to be noted that surprisingly that many of the
electrically photosensitive materials of the present invention as
described by formula I, are also useful as chemical sensitizers of
electrophotosensitive materials. Hence, the materials described by
formula I of the present invention may be used in electrophoretic
migration imaging processes as (1) an electrophotosensitive
material and/or chemical sensitizer in the formation of monochrome
images, (2) as a chemical sensitizer of other electrophotosensitive
material in the formation of monochrome images and/or (3) as an
electrophotosensitive material and/or a chemical sensitizer in the
formation of polychrome images. It will be understood that in a
mixture comprising a material described by formula I and at least
one other electrophotosensitive material, the formula I material
may act as both an electrophotosensitive material and a chemical
sensitizer.
Accordingly, as will be apparent upon comparing structural formula
I above with the materials disclosed in U.S. Pat. Nos. 3,246,983,
3,567,450, 3,653,887 and 3,873,312, it can be seen that structural
formula I includes certain materials as useful materials in
electrophoretic migration imaging processes which are not disclosed
in either of the two aforementioned patents, and also that
structural formula I excludes many materials which are disclosed as
useful photoconductors in these same patents. In brief, for reasons
not fully understood by applicants, it has been found that
materials having structural formula I hereinabove provide highly
useful electrophotosensitive materials and/or chemical sensitizers
for other electrically photosensitive materials for electrophoretic
migration imaging processes, whereas materials which may have
structural formulas quite similar to that shown in formula I and
which are known to possess useful photoconductive properties do not
serve as useful materials for electrophoretic migration imaging
processes.
In addition to the unexpected capability as sensitizers and the
unexpected useful levels of electrophotosensitivity exhibited by
the materials of formula I above in electrophoretic migration
imaging processes, in comparison with that exhibited by similar
organic photoconductive materials, the materials of formula I
generally exhibit certain other properties which make these
materials quite useful in electrophoretic migration imaging
processes. Among other such useful properties, the materials of
formula I are typically highly colored materials, generally
exhibiting an absorption maxima to visible light at a wavelength
greater than 410 nm, preferably in the 420 to 600 nm region of the
visible spectrum. Thus, these materials, in general, tend to have a
yellow, orange, or magenta hue. In contrast, many, although not
all, of the organic photoconductive materials described in U.S.
Pat. Nos. 3,246,983 and 3,567,450 are colorless materials. Also,
whereas many of the organic photoconductive materials described in
U.S. Pat. No. 3,246,983, 3,567,450, 3,653,887 and 3,873,312 are
soluble in conventional organic solvents, e.g., aliphatic
hydrocarbon solvents such as Isopar G.RTM. or alkylated aromatic
solvents such as Solvesso 100, and therefore can readily be coated
or cast, together with a binder, from conventional organic solvents
onto a conductive support to form photoconductive plates, webs,
drums and the like useful in conventional electrophotographic
applications, the materials of formula I tend to be highly
insoluble or only slightly soluble in such conventional organic
solvents. This latter property of substantial insolubility in
conventional organic solvents is advantageous in electrophoretic
migration imaging processes, particularly in those embodiments of
such processes wherein the electrically photosensitive material is
dispersed in particulate form in an electrically insulating carrier
such as a conventional aliphatic hydrocarbon liquid to form an
electrophoretic migration imaging suspension.
Typical electrically photosensitive colorant materials which may be
used in the present invention have the formula I illustrated
hereinabove.
The terms "substituted alkyl group" and "substituted aromatic ring
group" as used in the present application are defined to means
those substituents which do not interfere with the electrical
photosensitivity of the colorants used in the invention and which
are conventionally recognized in the art as typical substituents
for alkyl and aromatic groups, respectively. A partial listing of
representative such substituted alkyl groups includes the following
materials. Typically, these materials contain 1 to about 8 carbon
atoms in the alkyl group thereof.
a. alkoxyalkyl having a total of 2 to about 8 carbon atoms, e.g.,
ethoxypropyl, methoxybutyl, propoxymethyl, etc.
b. aryloxyalkyl, e.g., phenoxyethyl, naphthoxymethyl,
phenoxypentyl, etc.,
c. aminoalkyl, e.g., aminobutyl, aminoethyl, aminopropyl, etc.
d. hydroxyalkyl, e.g., hydroxypropyl, hydroxyoctyl, hydroxymethyl,
etc.,
e. aralkyl, e.g., benzyl, phenethyl, .omega.,.omega.-diphenylalkyl,
etc.,
f. alkylaminoalkyl, e.g., methylaminopropyl, methylaminoethyl,
etc., and also including dialkylaminoalkyl, e.g.,
diethylaminoethyl, dimethylaminopropyl, propylaminooctyl, etc.,
g. arylaminoalkyl, e.g., phenylaminoalkyl, diphenylaminoalkyl,
N-phenyl-N-ethylaminopentyl, N-phenyl-N-ethylaminohexyl,
naphthylaminomethyl, etc.,
h. nitroalkyl, e.g., nitrobutyl, nitroethyl, nitropentyl, etc.,
i. cyanoalkyl, e.g., cyanopropyl, cyanobutyl, cyanoethyl, etc.,
j. haloalkyl, e.g., chloromethyl, bromopentyl, chlorooctyl, etc.,
and,
k. alkyl substituted with an acyl group having the formula:
##STR3## wherein R is hydroxy, hydrogen, aryl, e.g., phenyl,
naphthyl, etc., lower alkyl having 1 to about 4 carbon atoms, e.g.,
methyl, ethyl, propyl, etc., amino including substituted amino,
e.g., diloweralkylamino, lower alkoxy having 1 to about 8 carbon
atoms, e.g., butoxy, methoxy, etc., aryloxy, e.g., phenoxy,
naphthoxy, etc.
A partial listing of representative substituted aromatic ring
groups includes the following materials. Typically, the substituent
groups on these aromatic materials contain from 1 to about 8 carbon
atoms.
a. alkoxyaryl, e.g., ethoxyphenyl, methoxyphenyl, propoxynaphthyl,
etc.,
b. aryloxyaryl, e.g., phenoxyphenyl, naphthoxyphenyl,
phenoxynaphthyl, etc.,
c. aminoaryl, e.g., aminophenyl, aminonaphthyl, aminoanthryl,
etc.,
d. hydroxyaryl, e.g., hydroxyphenyl, hydroxynaphthyl,
hydroxyanthryl, etc.,
e. biphenylyl,
f. alkylaminoaryl, e.g., methylaminophenyl, methylaminonaphthyl,
etc., and also including dialkylaminoaryl, e.g.,
diethylaminophenyl, dipropylaminophenyl, etc.,
g. arylaminoaryl, e.g., phenylaminophenyl, diphenylaminophenyl,
N-phenyl-N-ethylaminophenyl, naphthylaminophenyl, etc.,
h. nitroaryl, e.g., nitrophenyl, nitronaphthyl, nitroanthryl,
etc.,
i. cyanoaryl, e.g., cyanophenyl, cyanonaphthyl, cyanoanthryl,
etc.,
j. haloaryl, e.g., chlorophenyl, bromophenyl, chloronaphthyl,
etc.,
k. alkaryl, e.g., tolyl, ethylphenyl, propylnaphthyl, etc., and
l. aryl substituted with an acyl group having the formula: ##STR4##
wherein R is hydroxy, hydrogen, lower alkyl having 1 to about 4
carbon atoms, e.g., methyl, ethyl, propyl, butyl, etc., aryl, e.g.,
phenyl, naphthyl, etc., amino including substituted amino, e.g.,
diloweralkylamino, lower alkoxy having 1 to about 8 carbon atoms,
e.g., butoxy, methoxy, etc., aryloxy, e.g., phenoxy, naphthoxy,
etc.
Within the class of materials having formula I above, three
individual subclasses of materials have been found to exhibit
particularly useful properties for electrophoretic migration
imaging processes. These three subclasses of materials may be
represented by the following structural formulas: ##STR5## wherein
Ar is as defined hereinabove; each of R.sup.4 and R.sup.5, which
may be the same or different, represents hydrogen or a cyano group;
and each of R.sup.7, R.sup.8, R.sup.9, R.sup.10 and R.sup.11, when
taken alone, represents a substituted or unsubstituted, acyclic
lower alkyl having 1 to about 8 carbon atoms or a substituted or
unsubstituted, carbocyclic aromatic ring group preferably having 6
to about 14 ring atoms in the aromatic ring, such as an aryl group,
e.g., phenyl, or an alkaryl, e.g., tolyl, ethylphenyl, etc., and
R.sup.7 and R.sup.8, when taken together, represent a pyrrolidinyl
or a piperidino group.
In general, the photosensitive materials of formula I above which
have, to date, been found most useful in the present invention
because of their high degree of photosensitivity and other
desirable properties, for example, color separation in multicolor
electrophoretic migration imaging processes and the like, tend to
exhibit a yellow or orange coloration and a maximum absorption
wavelength, .lambda.max, within the range of from about 420 to
about 600 nm. Although photosensitive materials represented by
formulas II-IV above have generally been found most useful among
the various materials described within the general class having
formula I, a variety of different materials within the class
defined by formula I have been tested and found to exhibit useful
levels of electrical photosensitivity in electrophoretic migration
imaging processes. A partial listing of representative such
materials is included herein in Table 1.
Table 1
__________________________________________________________________________
Com- pound No. Compound Structure
__________________________________________________________________________
1 ##STR6## 2 ##STR7## 3 ##STR8## 4 ##STR9## 5 ##STR10## 6 ##STR11##
7 ##STR12## 8 ##STR13## 9 ##STR14## 10 ##STR15## 11 ##STR16## 12
##STR17## 13 ##STR18## 14 ##STR19## 15 ##STR20## 16 ##STR21## 17
##STR22## 18 ##STR23## 19 ##STR24## 20 ##STR25## 21 ##STR26## 22
##STR27## 23 ##STR28## 24 ##STR29## 25 ##STR30## 26 ##STR31## 27
##STR32## 28 ##STR33## 29 ##STR34## 30 ##STR35## 31 ##STR36## 32
##STR37## 32a ##STR38## 32b ##STR39## 33 ##STR40##
__________________________________________________________________________
As indicated hereinabove, the electrically photosensitive colorant
material described herein is useful in the preparation of
electrically photosensitive imaging particles of electrophoretic
migration imaging processes. In general, electrically
photosensitive particles useful in such processes have an average
particle size within the range of from about 0.01 micron to about
20 microns, preferably from about 0.01 to about 5 microns.
Typically, these particles are composed of one or more colorant
materials such as those described in the present invention.
However, these electrically photosensitive particles may also
contain various nonphotosensitive materials such as electrically
insulating polymers, charge control agents, various organic and
inorganic fillers, as well as various additional dyes or pigment
materials to change or enhance various colorant and physical
properties of the electrically photosensitive particle. In
addition, such electrically photosensitive particles may contain
other photosensitive materials such as various sensitizing dyes
and/or chemical sensitizers to alter or enhance their response
characteristics to activating radiation.
Also as stated hereinabove, the materials described by formulas
I-V, are useful as chemical sensitizers for electrophotosensitive
particles used in electrophoretic migration imaging processes
and/or as electrophotosensitive materials in electrophoretic
migration imaging processes. When used in an electrophoretic
migration imaging process in accord with the present invention, the
electrically photosensitive material described by formulas I-V
hereinabove, whether used for the electrophotosensitive properties
or as chemical sensitizers are typically positioned in particulate
form, between two or more spaced electrodes, one or both of which
typically being transparent to radiation to which the electrically
photosensitive material is light-sensitive, i.e., activating
radiation. Although the electrically photosensitive material, in
particulate form, may be dispersed simply as a dry powder between
two spaced electrodes and then subjected to a typical
electrophoretic migration imaging operation such as that described
in U.S. Pat. No. 2,758,939 by Sugarman referenced hereinabove, it
is more typical to disperse the electrically photosensitive
particulate material in an electrically insulating carrier, such as
an electrically insulating liquid, or an electrically insulating,
liquefiable matrix material, such as a heat- and/or
solvent-softenable polymeric material or a thixotropic polymeric
material. Typically, when one employs such a dispersion of
electrically photosensitive particulate material and electrically
insulating carrier material between the spaced electrodes of an
electrophoretic migration imaging system, it is conventional to
employ from about 0.05 part to about 2.0 parts of electrically
photosensitive particulate material for each 10 parts by weight of
electrically insulating carrier material.
As indicated above, when the electrically photosensitive particles
used in the present invention are dispersed in an electrically
insulating carrier material, such carrier material may assume a
variety of physical forms and may be selected from a variety of
different materials. For example, the carrier material may be a
matrix of an electrically insulating, normally solid polymeric
material capable of being softened or liquefied upon application of
heat, solvent, and/or pressure so that the electrically
photosensitive particulate material dispersed therein can migrate
through the matrix. In another, more typical embodiment of the
invention, the carrier material can comprise an electrically
insulating liquid such as decane, paraffin, Sohio Oderless Solvent
3440 (a kerosene fraction marketed by the Standard Oil Company,
Ohio), various isoparaffinic hydrocarbon liquids such as those sold
under the trademark Isopar G by Exxon Corporation and having a
boiling point in the range of 145.degree. C. to 186.degree. C.,
various halogenated hydrocarbons such as carbon tetrachloride,
trichloromonofluoromethane, and the like, various alkylated
aromatic hydrocarbon liquids such as the alkylated benzenes, for
example, xylenes, and other alkylated aromatic hydrocarbons such as
are described in U.S. Pat. No. 2,899,335. An example of one such
useful alkylated aromatic hydrocarbon liquid which is commercially
available is Solvesso 100 made by Exxon Corp. Solvesso 100 has a
boiling point in the range of about 157.degree. C. to about
177.degree. C. and is composed of 9 percent xylene, 16 percent of
other monoalkyl benzenes, 34 percent dialkyl benzenes, 37 percent
trialkyl benzenes, and 4 percent aliphatics. Typically, whether
solid or liquid at normal room temperatures, i.e., about 22.degree.
C., the electrically insulating carrier material used in the
present invention is a material having a resistivity greater than
about 10.sup.9 ohm-cms, preferably greater than about 10.sup.12
ohm-cm. When the electrically photosensitive particles used in the
present invention are incorporated in a carrier material, such as
one of the above-described electrically insulating liquids, various
other addenda may also be incorporated in the resultant imaging
suspension. For example, various charge control agents may be
incorporated in such a suspension to improve the uniformity of
charge polarity of the electrically photosensitive particles
dispersed in the liquid suspension. Such charge control agents are
well known in the field of liquid electrographic developer
compositions where they are employed for purposes substantially
similar to that described herein. Thus, extensive discussion of
these materials herein is deemed unnecessary. These materials are
typically polymeric materials incorporated by admixture thereof
into the liquid carrier vehicle of the suspension. In addition to,
and possibly related to, the aforementioned enhancement of uniform
charge polarity, it has been found that the charge control agents
often provide more stable suspensions, i.e., suspensions which
exhibit substantially less settling out of the dispersed
photosensitive particles.
In addition to the foregoing charge control agent materials,
various polymeric binder materials such as various natural,
semi-synthetic or synthetic resins, may be dispersed or dissolved
in the electrically insulating carrier to serve as a fixing
material for the final photosensitive particle image formed on one
of the spaced electrodes used in electrophoretic migration imaging
systems. Here again, the use of such fixing addenda is conventional
and well known in the closely related art of liquid electrographic
developer compositions so that extended discussion thereof is
unnecessary herein.
The process of the present invention will be described in more
detail with reference to the accompanying drawing, FIG. 1, which
illustrates a typical apparatus which employs the electrophoretic
migration imaging process of the invention.
FIG. 1 shows a transparent electrode 1 supported by two rubber
drive rollers 10 capable of imparting a translating motion to
electrode 1 in the direction of the arrow. Electrode 1 may be
composed of a layer of optically transparent material, such as
glass or an electrically insulating, transparent polymeric support
such as polyethylene terephthalate, covered with a thin, optically
transparent, conductive layer such as tin oxide, indium oxide,
nickel, and the like. Optionally, depending upon the particular
type of electrophoretic migration imaging process desired, the
surface of electrode 1 may bear a "dark charge exchange" material,
such as a solid solution of an electrically insulating polymer and
2,4,7, trinitro-9-fluorenone as described by Groner in U.S. Pat.
No. 3,976,485 issued Aug. 24, 1976.
Spaced opposite electrode 1 and in pressure contact therewith is a
second electrode 5, an idler roller which serves as a counter
electrode to electrode 1 for producing the electric field used in
the electrophoretic migration imaging process. Typically, electrode
5 has on the surface thereof a thin, electrically insulating layer
6. Electrode 5 is connected to one side of the power source 15 by
switch 7. The opposite side of the power source 15 is connected to
electrode 1 so that as an exposure takes place, switch 7 is closed
and an electric field is applied to the electrically photosensitive
particulate material 4 which is positioned between electrodes 1 and
5. Typically electrically photosensitive particulate material 4 is
dispersed in an electrically insulating carrier material such as
described hereinabove.
The electrically photosensitive particulate material 4 may be
positioned between electrodes 1 and 5 by applying material 4 to
either or both of the surfaces of electrodes 1 and 5 prior to the
imaging process or by injecting electrically photosensitive imaging
material 4 between electrodes 1 and 5 during the electrophoretic
migration imaging process.
As shown in FIG. 1, exposure of electrically photosensitive
particulate material 4 takes place by use of an exposure system
consisting of light source 8, an original image 11 to be
reproduced, such as a photographic transparency, a lens system 12,
and any necessary or desirable radiation filters 13, such as color
filters, whereby electrically photosensitive material 4 is
irradiated with a pattern of activating radiation corresponding to
original image 11. Although the electrophoretic migration imaging
system represented in FIG. 1 shows electrode 1 to be transparent to
activating radiation from light source 8, it is possible to
irradiate electrically photosensitive particulate material 4 in the
nip 21 between electrodes 1 and 5 without either of electrodes 1 or
5 being transparent. In such a system, although not shown in FIG.
1, the exposure source 8 and lens system 12 is arranged so that
image material 4 is exposed in the nip or gap 21 between electrodes
1 and 5.
As shown in FIG. 1, electrode 5 is a roller electrode having a
conductive core 14 connected to power source 15. The core is in
turn covered with a layer of insulating material 6, for example,
baryta paper. Insulating material 6 serves to prevent or at least
substantially reduce the capability of electrically photosensitive
particulate material 4 to undergo a radiation induced charge
alteration upon interaction with electrode 5. Hence, the term
"blocking electrode" may be used, as is conventional in the art of
electrophoretic migration imaging, to refer to electrode 5.
Although electrode 5 is shown as a roller electrode and electrode 1
is shown as essentially a translatable, flat plate electrode in
FIG. 1, either or both of these electrodes may assume a variety of
different shapes such as a web electrode, rotating drum electrode,
plate electrode, and the like as is well known in the field of
electrophoretic migration imaging. In general, during a typical
electrophoretic migration imaging process wherein electrically
photosensitive material 4 is dispersed in an electrically
insulating, liquid carrier, electrodes 1 and 5 are spaced such that
they are in pressure contact or very close to one another during
the electrophoretic migration imaging process, e.g., less than 50
microns apart. However, where electrically photosensitive
particulate material 4 is dispersed simply in an air gap between
electrodes 1 and 5 or in a carrier such as a layer of
heat-softenable or other liquefiable material coated as a separate
layer on electrode 1 and/or 5, these electrodes may be spaced more
than 50 microns apart during the imaging process.
The strength of the electric field imposed between electrodes 1 and
5 during the electrophoretic migration imaging process of the
present invention may vary considerably; however, it has generally
been found that optimum image density and resolution are obtained
by increasing the field strength to as high a level as possible
without causing electrical breakdown of the carrier medium in the
electrode gap. For example, when electrically insulating liquids
such as isoparaffinic hydrocarbons are used as the carrier in the
imaging apparatus of FIG. 1, the applied voltage across electrodes
1 and 5 typically is within the range of from about 100 volts to
about 4 kilovolts or higher.
As explained hereinabove, image formation occurs in electrophoretic
migration imaging processes as the result of the combined action of
activating radiation and electric field on the electrically
photosensitive particulate material 4 disposed between electrodes 1
and 5 in the attached drawing. Typically, for best results, field
application and exposure to activating radiation occur
concurrently. However, as would be expected, by appropriate
selection of various process parameters such as field strength,
activating radiation intensity, incorporation of suitable light
sensitive addenda in or together with the electrically
photosensitive material of formula I used in the present invention,
e.g., by incorporation of a persistent photoconductive material,
and the like, it is possible to alter the timing of the exposure
and field application events so that one may use sequential
exposure and field application events rather than concurrent field
application and exposure events.
When disposed between imaging electrodes 1 and 5 of FIG. 1,
electrically photosensitive particulate material 4 exhibits an
electrostatic charge polarity, either as a result of triboelectric
interaction of the particles or as a result of the particles
interacting with the carrier material in which they are dispersed,
for example, an electrically insulating liquid, such as occurs in
conventional liquid electrographic developing compositions composed
of toner particles which acquire a charge upon being dispersed in
an electrically insulating carrier liquid.
Image discrimination occurs in the electrophoretic migration
imaging process of the present invention as a result of the
combined application of electric field and activating radiation on
the electrically photosensitive particulate material dispersed
between electrodes 1 and 5 of the apparatus shown in FIG. 1. That
is, in a typical imaging operation, upon application of an electric
field between electrodes 1 and 5, the particles 4 of
charge-bearing, electrically photosensitive material are attracted
in the dark to either electrodes 1 or 5, depending upon which of
these electrodes has a polarity opposite to that of the original
charge polarity acquired by the electrically photosensitive
particles. And, upon exposing particles 4 to activating
electromagnetic radiation, it is theorized that there occurs
neutralization or reversal of the charge polarity associated with
either the exposed or unexposed particles. In typical
electrophoretic migration imaging systems wherein electrode 1 bears
a conductive surface, the exposed, electrically photosensitive
particles 4, upon coming into electrical contact with such
conductive surface, undergo an alteration (usually a reversal) of
their original charge polarity as a result of the combined
application of electric field and activating radiation.
Alternatively, in the case wherein the surface of electrode 1 bears
a dark charge exchange material as described by Groner in
aforementioned U.S. Pat. No. 3,976,485, one obtains reversal of the
charge polarity of the unexposed particles, while maintaining the
original charge polarity of the exposed electrically photosensitive
particles, as these particles come into electrical contact with the
dark charge exchange surface of electrode 1. In any case, upon the
application of electric field and activating radiation to
electrically photosensitive particulate material 4 disposed between
electrodes 1 and 5 of the apparatus shown in FIG. 1, one can
effectively obtain image discrimination so that an image pattern is
formed by the electrically photosensitive particles which
corresponds to the original pattern of activating radiation.
Typically, using the apparatus shown in FIG. 1, one obtains a
visible image on the surface of electrode 1 and a complementary
image pattern on the surface of electrode 5.
Subsequent to the application of the electric field and exposure to
activating radiation, the images which are formed on the surface of
electrodes 1 and/or 5 of the apparatus shown in FIG. 1 may be
temporarily or permanently fixed to these electrodes or may be
transferred to a final image receiving element. Fixing of the final
particle image can be effected by various techniques, for example,
by applying a resinous coating over the surface of the image
bearing substrate. For example, if electrically photosensitive
particles 4 are dispersed in a liquid carrier between electrodes 1
and 5, one may fix the image or images formed on the surface of
electrodes 1 and/or 5 by incorporating a polymeric binder material
in the carrier liquid. Many such binders (which are well known for
use in liquid electrophotographic liquid developers) are known to
acquire a change polarity upon being admixed in a carrier liquid
and therefore will, themselves, electrophoretically migrate to the
surface of one or the other of the electrodes. Alternatively, a
coating of a resinous binder (which has been admixed in the carrier
liquid), may be formed on the surfaces of electrodes 1 and/or 5
upon evaporation of the liquid carrier.
The electrically photosensitive colorant material used in the
imaging process of the present invention may be used to form
monochrome images, or the material may be admixed with other
electrically photosensitive material of proper color and
photosensitivity and used to form polychrome images. Said
electrically photosensitive colorant material of the present
invention also may be used as a sensitizer for other
electrophotosensitive material in the formation of monochrome
images. When admixed with other electrically photosensitive
materials, selectively the photosensitive material of the present
invention may act as a sensitizer and/or as an electrically
photosensitive particle. As indicated, many of the electrically
photosensitive colorant materials having formula I described herein
have an especially useful yellow or orange hue and therefore are
particularly suited for use in polychrome imaging processes which
employ a mixture of two or more differently colored electrically
photosensitive particles, e.g., a mixture of cyan particles which
are principally sensitive to red light, magenta particles which are
principally sensitive to green light, and yellow or orange
particles containing the electrically photosensitive colorant
materials described in the present invention which are principally
sensitive to blue light. When such a mixture of multicolored
electrically photosensitive particles is formed, for example, in an
electrically insulating carrier liquid, this liquid mixture of
particulate material exhibits a black coloration. Preferably, the
specific cyan, magenta, and yellow particles selected for use in
such a polychrome imaging process are chosen so that their spectral
response curves do not appreciably overlap whereby color separation
and subtractive multicolor image reproduction can be achieved.
The following examples illustrate the invention, the parts and
percentages being by weight unless otherwise stated.
EXAMPLES
Image Evaluation Apparatus
An image evaluation apparatus was used in each of the succeeding
examples to carry out the electrophoretic migration imaging process
described herein. This apparatus was a device of the type
illustrated in FIG. 1. In this apparatus, a translating NESA or
NESATRON (trademarks of PPG for a conductive tin oxide treated
glass or a conductive indium oxide sputtered glass, respectively)
glass plate served as electrode 1 and was in pressure contact with
a 10 centimeter diameter aluminum roller 14 covered with a thin
insulating layer of poly(vinyl butyral)-TiO.sub.2 coated paper 6
which served as electrode 5. NESA plate 1 was supported by two 2.8
cm. diameter rubber drive rollers 10 positioned beneath NESA plate
1 such that a 2.5 cm. opening, symmetric with the axis of the
aluminum roller 14, existed to allow exposure of electrically
photosensitive particles 4 to activating radiation. The original
transparency 11 to be reproduced was taped to the back side of NESA
plate 1. The exposing activating radiation was supplied from a
light source 8 consisting of a Kodak Carousel projector and had a
maximum intensity of 3500 footcandles at the NESA glass plate
exposure plane. The voltage between the electrode 5 and NESA plate
1 was variable up to 10 kilovolts. However, most tests were made in
the 0.5 to 2 kv range. NESA plate 1 was negative polarity in the
case where electrically photosensitive particulate material 4
carried a positive electrostatic charge, and NESA plate 1 was
positive in the case where electrically photosensitive
electrostatically charged particles were negatively charged. The
translational speed of NESA plate 1 was variable between about 1.25
cm. and about 30 cm. per second. In the following examples, image
formation occurs on the surfaces of NESA glass plate 1 and
electrode 5 after simultaneous application of light exposure and
electric field to electrically photosensitive particulate material
4. In this image evaluation apparatus, each different type of
material to be evaluated for use as electrically photosensitive
particulate material 4 was admixed with a liquid carrier as
described below to form a liquid imaging dispersion which was
placed in nip 21 between the electrodes 1 and 5. If the material
being evaluated for use as material 4 possessed a useful level of
electrical photosensitivity, one obtained a negative-appearing
image reproduction of original 11 on electrode 5 and a
complementary image on electrode 1.
Imaging Dispersion Preparation
In the following examples a series of 46 different imaging
dispersions were prepared to evaluate various types of materials
for electrical photosensitivity. These dispersions were prepared by
ball-milling the various materials to be tested for electrical
photosensitivity at high concentration with a polymeric charge
control agent and then diluting the resultant mixture with another
polymer solution, such as by ultrasonic agitation. The exact ratios
of the various materials used in the initial high concentration
ball-mill concentrate and subsequent polymer solution are outlined
below:
Ball-Mill Concentrate
1. 1 gram of material to be tested for electrical photosensitive
properties,
2. 1 gram of polymeric charge control agent consisting of a
copolymer of vinyl toluene, lauryl methacrylate, lithium
methacrylate, and methacrylic acid, the monomeric weight percent
ratio of vinyl toluene to lauryl methacrylate to lithium
methacrylate to methacrylic acid being as follows: 56:40:3.6:0.4,
respectively.
3. 110 grams of stainless steel balls having a diameter of about 3
mm., and
4. 12.2 grams of carrier liquid consisting of Solvesso 100
(purchased from the Exxon Corporation) or, alternatively, 10.7
grams of Isopar.RTM. G (purchased from the Exxon Corporation).
Each of the ball-mill concentrates having the above-noted
composition were ball-milled in a 125 milliliter glass jar at 115
revolutions per minute for at least one week. The ball-mill
concentrates were then diluted by adding 35.8 grams of a 40% by
weight solution of Piccotex 100 (a styrene-toluene copolymer
purchased from the Pennsylvania Industrial Chemical Corporation) in
Isopar.RTM. G at a rate of 15 milliliters per minute through a
hollow ultrasonic probe. During this dilution operation the
temperature of the imaging dispersion thus being formed was
maintained at approximately 20.degree. C.
EXAMPLES 1-32
Table 2 hereinafter contains the results for 46 different materials
evaluated for electrical photosensitivity properties for use in
electrophoretic migration imaging. The first 32 materials evaluated
in Table 2 correspond to the 32 materials set forth hereinbefore in
Table 1. Each of these 32 different materials had a formula within
structural formula I set forth hereinbefore and exhibited
electrical photosensitivity when tested in a migration imaging
process using the image evaluation apparatus as outlined above.
However, the last 14 materials, i.e., materials 33-46 displayed no
electrical photoresponse under these same evaluation conditions.
However, material 33 does act as a chemical sensitizer as will be
shown in other examples. Each of these last 13 materials tested had
a structural formula outside the scope of formula I and therefore
outside the scope of the present invention. However, the structural
formula of the materials labeled 34-46 is quite similar to
structural formula I, thereby indicating the surprising aspect of
the present invention wherein it has been found that, for the
particular class of known organic photoconductive materials tested
herein, certain of these materials display useful levels of
electrical photosensitivity or chemical sensitization suitable for
electrophoretic migration imaging processes (i.e., see materials
1-33 of Table 2), whereas other closely related materials within
this same general class of known organic photo-conductors do not
possess useful levels of electrical photosensitivity in
electrophoretic migration imaging (i.e., see materials 34-46 of
Table 2). In Table 2, the speed of the NESA plate electrode 1 used
in the above-described image evaluation apparatus is noted as well
as various other evaluation parameters. Since materials 1-32 and 33
are identical to compounds 1-32 and 33 of Table 1, their structure
is not presented in Table 2. Useful images are obtained with each
of compounds 1-32 under the test conditions noted in Table 2.
Table 2 ______________________________________ Exposure Com-
Filters Nesa Glass pound Milling* Particle (Neutral Speed No.
Liquid Polarity Density) (cm/sec) .lambda..sub.max (nm)
______________________________________ 1 S + 1.2 25 480 2 S + 1.2
25 470 3 I + 1.0 25 470 4 S + None Used 25 490 5 S + None Used 25
440 6 S + None Used 25 455 7 S + None Used 25 520 8 I + None Used
25 465 9 S + None Used 25 10 S + None Used 25 425 11 I + None Used
25 415 12 S - None Used 25 13 S + None Used 25 450 14 S + None Used
25 520 15 S - None Used 25 480 16 S + None Used 2.5 17 S + None
Used 2.5 430 18 S + None Used 2.5 450 19 S + None Used 25 460 20 I
+ None Used 25 430 21 I - None Used 25 460 22 I + None Used 25 465
23 I + None Used 25 460 24 I + None Used 25 450 25 S + None Used
2.5 450 26 S + None Used 2.5 450 27 S + None Used 25 480 28 S +
None Used 25 520 29 I + None Used 25 430 30 I + None Used 25 460 31
S + None Used 25 470 32 S + None Used 25 480 The following
compounds 33-48 failed to give an image under the evaluation
conditions 33 34 ##STR41## 35 ##STR42## 36 ##STR43## 37 ##STR44##
38 ##STR45## 39 ##STR46## 40 ##STR47## 41 ##STR48## 42 ##STR49## 43
##STR50## 44 ##STR51## 45 ##STR52## 46 ##STR53##
______________________________________ *S Solvesso 100 I
Isopar.RTM. G
EXAMPLE 49
In this example, the use of the materials described by structural
formula I herein in a polychrome electrophoretic migration imaging
process was demonstrated. In this example, three separate cyan,
magenta and yellow monochrome dispersions were prepared. Each such
monochrome dispersion was prepared using the dispersion preparation
technique outlined above. The electrically photosensitive material
used as the photosensitive and colorant material in the cyan
dispersion was Cyan Blue GTNF, Colour Index No. 74160, a beta form
of copper phthalocyanine available from American Cyanamid. The
electrically photosensitive material used as the photosensitive and
colorant material in the magenta dispersion was Sandorin Brilliant
Red 5BL, a quinacridine pigment similar or identical to Pigment Red
192 of the Colour Index and available from the Sandoz Corporation.
The electrically photosensitive material used as the photosensitive
and colorant material of the yellow dispersion was material 9 of
Tables 1 and 2, i.e., 9,10-bis[4-(tolylamino)styryl]anthra-cene.
After preparing each of the above-described monochrome dispersions,
these three dispersions were admixed together in a volume ratio of
cyan to magenta to yellow of 1:1:1. The resultant "trimix"
dispersion was used to form multicolor electrophoretic migration
images using the above-described image evaluation apparatus. In
this multicolor imaging example, the intensity of the imagewise
exposure on the plane of the NESA plate was 2000 footcandles and
the translational speed of the NESA plate during the multicolor
imaging operation was about 30 cm./sec. A Kodak Wratten 2B filter
was included in the exposure beam of light. The voltage between
electrode 5 and NESA plate 1 was maintained at 1 kilovolt during
the imaging operation. As a result, it was found that a good
quality three-color negative-to-positive print was formed on
blocking layer 6 of electrode 5 and, also, a good
positive-to-positive multicolor print was formed on the surface of
NESA plate 1.
EXAMPLES 50-58
The following examples were carried out to demonstrate the
capabilities of the electrophotosensitive materials of formula I as
chemical sensitizers. Each dispersion in said examples was prepared
according to a procedure which was substantially similar to the
procedure used to prepare the dispersions of Examples 1-32. The
apparatus used for formation of the images was substantially
similar to that shown in FIG. 1 except that in some cases, a
translating roller stationary glass plate electrode was used
instead of the stationary roller electrode-translating glass plate
embodiment of the apparatus.
EXAMPLE 50
Cyan, magenta, and yellow dispersions were prepared using Phthalo
Blue Powder, Sandorin Brilliant Red 5BL, and compound 8 from Table
1 respectively. These dispersions were prepared according to a
procedure substantially similar to that used to prepare the
dispersions of Examples 1-32.
Small amounts of these three dispersions were placed adjacent to
each other in the nip of a translating roller apparatus similar to
that shown in FIG. 1 for imaging. The yellow dispersion was placed
between the cyan and magenta dispersions. It was observed that the
image on the roller blocking electrode showed an increase in print
density for both the cyan and magenta prints in the regions of
overlap with the yellow dispersion. This increase in density was
especially noticeable for the cyan dispersion.
Portions of these three dispersions were mixed together in the
ratio of 6/4/3, compound 8 (yellow)/cyan/magenta and imaged as
above. The test target consisted of adjacent Kodak Wratten 70
(red), 58 (green) and 47B (blue) filters superimposed with a
Kodalith film containing clear letters on a dark background. The
resulting negative-to-positive multicolor roller record had greater
image density, especially for the cyan, than would have been
predicted from the non-overlapped monochrome from the previous
test.
The translational speed of the roller electrode was 20 cm/sec, for
the above tests. The light intensity was 4000 foot candles, and the
voltage on the NESA glass plate electrode was -1000 volts.
EXAMPLES 51-58
Eight separate yellow pigment dispersions were prepared using eight
of the compounds from Table 1. Controlled magenta and cyan pigment
dispersions were also prepared. The pigments for the two controls
were of Sandorin Brilliant Red 5BL and Cyan Blue GTNF respectively.
All dispersions were prepared according to Example 50.
The eight yellow pigment dispersions using compounds taken from
Table 1 were used as sensitizers for the control magenta and cyan
dispersions. Said yellow pigment dispersions were used as two
different concentration levels. The levels were 1 and 5 part
sensitizer dispersion to 50 parts of each of the control
dispersion. This amounted to sensitizer concentrations of 0.04% and
0.18%. Other experimental conditions were as follows.
Light intensity: 2000 fc modified by a Kodak Wratten 2A filter and
a 665 nm interference cutoff filter.
Electrode potential: -1500 volts on NESATRON glass plate.
Plate translational speed: 23 cm/sec for cyan and 15 cm/sec for
magenta.
The test pattern used for testing these dispersions consisted of
adjacent red, green, and blue filters (Kodak Wratten 29, 61, and 47
filters, respectively) each superimposed with a 0.3 ND step
wedge.
To evaluate the speed increase due to the presence of a sensitizer,
the light intensity needed to produce a mid-range print reflection
density resulting from a color exposure complementary to the
dispersion's color was compared to the intensity needed to produce
the same reflection density with the control dispersion. For an
example, the relative red light intensities for the same mid-range
red, print reflection density were compared for the sensitized and
unsensitized cyan dispersions and the speed increase calculated.
This was also done for the magenta dispersion. The print density
for the other color exposures corresponding to unwanted absorptions
was measured in the same manner. The ratios of the speed increase
for the primary to unwanted absorptions for the sensitized and
unsensitized control were calculated and compared. These were
identical within experimental error and, thus, it was concluded
that the sensitization was primarily chemical rather than spectral
in nature.
Table 3 lists the relative speed increases for the two sensitizer
concentration levels relative to the unsensitized controls.
When one of these yellow sensitizer dispersions is used as one of
the three components making up a tricolor dispersion, it functions
not only as the primary colorant, but, also as a sensitizer for the
magenta and cyan with no detrimental spectral shifts.
Table 3 ______________________________________ Relative Speed
Increase Sensitized Magenta Sensitized Cyan (Sensitizer (Sensitizer
Compound From Concentration) Concentration) Table 1 0.04% 0.18%
0.04% 0.18% ______________________________________ 1 8 8 10 10 2 35
35 10 16 3 8 16 10 10 9 4 8 8 8 5 2 4 3 3 14 2 2 2 2 32b 16 8 16 16
33 4 4 8 8 ______________________________________
The invention has been described in detail with particular
reference to certain preferred embodiments thereof, but it will be
understood that variations and modifications can be effected within
the spirit and scope of the invention.
* * * * *